"Meditation, although not often advertised as such, can work dramatic changes on the brain via concentration or the non-judgmental awareness of mental contents. When thinking quiets down and sensory input is at a minimum, very different sorts of feelings can arise, some of which are extraordinarily unlike normal waking consciousness. Although meditation is not an easy art, the potential rewards are great for those who have the knack and put in the time. The states of consciousness accessed, naturalistically understood, are just more brain states, but they can have directly felt qualities of unity and acceptance that mark them off as subjectively quite special, and that correspond to empirically-grounded cognitions."
— Thomas W. Clark, Spirituality without Faith